[PATCH] Properly honor no_sanitize_undefined attribute

[Marek Polacek <polacek at redhat dot com>]

Apparently I didn't pay much attention to no_sanitize_undefined
attribute when adding new features to ubsan, so we would instrument
stuff even though the function is marked with this attribute.
Thus fixed & new testcases added.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2014-06-30  Marek Polacek  <polacek@redhat.com>

	* convert.c (convert_to_integer): Don't instrument conversions if the
	function has no_sanitize_undefined attribute.
	* ubsan.c: Don't run the ubsan pass if the function has
	no_sanitize_undefined attribute.
c/
	* c-decl.c (grokdeclarator): Don't instrument VLAs if the function
	has no_sanitize_undefined attribute.
cp/
	* cp-gimplify.c (cp_genericize): Don't instrument returns if the
	function has no_sanitize_undefined attribute.
	* decl.c (compute_array_index_type): Don't instrument VLAs if the
	function has no_sanitize_undefined attribute.
testsuite/
	* c-c++-common/ubsan/attrib-2.c: New test.
	* g++.dg/ubsan/return-3.C: New test.

diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index def10a2..7895510 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -5505,7 +5505,11 @@ grokdeclarator (const struct c_declarator *declarator,
 		    this_size_varies = size_varies = true;
 		    warn_variable_length_array (name, size);
 		    if (flag_sanitize & SANITIZE_VLA
-		        && decl_context == NORMAL)
+		        && decl_context == NORMAL
+			&& current_function_decl != 0
+			&& !lookup_attribute ("no_sanitize_undefined",
+					      DECL_ATTRIBUTES
+						(current_function_decl)))
 		      {
 			/* Evaluate the array size only once.  */
 			size = c_save_expr (size);
diff --git gcc/convert.c gcc/convert.c
index 2d9600d..dbb59da 100644
--- gcc/convert.c
+++ gcc/convert.c
@@ -847,7 +847,10 @@ convert_to_integer (tree type, tree expr)
       return build1 (CONVERT_EXPR, type, expr);
 
     case REAL_TYPE:
-      if (flag_sanitize & SANITIZE_FLOAT_CAST)
+      if (flag_sanitize & SANITIZE_FLOAT_CAST
+	  && current_function_decl != 0
+	  && !lookup_attribute ("no_sanitize_undefined",
+				DECL_ATTRIBUTES (current_function_decl)))
 	{
 	  expr = save_expr (expr);
 	  tree check = ubsan_instrument_float_cast (loc, type, expr);
diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
index 296bd5f..dfa954b 100644
--- gcc/cp/cp-gimplify.c
+++ gcc/cp/cp-gimplify.c
@@ -1221,7 +1221,7 @@ cp_genericize_tree (tree* t_p)
 
 /* If a function that should end with a return in non-void
    function doesn't obviously end with return, add ubsan
-   instrmentation code to verify it at runtime.  */
+   instrumentation code to verify it at runtime.  */
 
 static void
 cp_ubsan_maybe_instrument_return (tree fndecl)
@@ -1334,7 +1334,10 @@ cp_genericize (tree fndecl)
      walk_tree's hash functionality.  */
   cp_genericize_tree (&DECL_SAVED_TREE (fndecl));
 
-  if (flag_sanitize & SANITIZE_RETURN)
+  if (flag_sanitize & SANITIZE_RETURN
+      && current_function_decl != 0
+      && !lookup_attribute ("no_sanitize_undefined",
+			    DECL_ATTRIBUTES (current_function_decl)))
     cp_ubsan_maybe_instrument_return (fndecl);
 
   /* Do everything else.  */
diff --git gcc/cp/decl.c gcc/cp/decl.c
index d548f61..861e7a8 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -8469,7 +8469,11 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
 			     throw_bad_array_length (), void_node);
 	      finish_expr_stmt (comp);
 	    }
-	  else if (flag_sanitize & SANITIZE_VLA)
+	  else if (flag_sanitize & SANITIZE_VLA
+		   && current_function_decl != 0
+		   && !lookup_attribute ("no_sanitize_undefined",
+					 DECL_ATTRIBUTES
+					   (current_function_decl)))
 	    {
 	      /* From C++1y onwards, we throw an exception on a negative
 		 length size of an array; see above.  */
diff --git gcc/testsuite/c-c++-common/ubsan/attrib-2.c gcc/testsuite/c-c++-common/ubsan/attrib-2.c
index e69de29..71f2e58 100644
--- gcc/testsuite/c-c++-common/ubsan/attrib-2.c
+++ gcc/testsuite/c-c++-common/ubsan/attrib-2.c
@@ -0,0 +1,71 @@
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=undefined -fsanitize=float-divide-by-zero -fsanitize=float-cast-overflow" } */
+
+/* Test that we don't instrument functions marked with
+   no_sanitize_undefined attribute.  */
+
+#ifndef __cplusplus
+#define bool _Bool
+#endif
+enum A { B = -3, C = 2 } a;
+bool b;
+
+__attribute__((no_sanitize_undefined))
+static void
+vla_bound (void)
+{
+  int i = -1;
+  volatile int a[i];
+}
+
+__attribute__((no_sanitize_undefined))
+static void
+si_overflow (void)
+{
+  int x = 123, y = 267;
+  volatile int z1 = x + y;
+  volatile int z2 = x - y;
+  volatile int z3 = x * y;
+  volatile int z4 = x / y;
+}
+
+__attribute__((no_sanitize_undefined))
+static void
+null (int *p)
+{
+  *p = 42;
+}
+
+__attribute__((no_sanitize_undefined))
+static void
+retrn (int *p)
+{
+  *p = 42;
+}
+
+__attribute__((no_sanitize_undefined))
+static enum A
+bool_enum (bool *p)
+{
+  *p = b;
+  return a;
+}
+
+__attribute__((no_sanitize_undefined))
+static void
+float_zero (void)
+{
+  volatile float a = 4.2f, b = 0.0f, c;
+  c = a / b;
+}
+
+__attribute__((no_sanitize_undefined))
+static void
+float_cast (void)
+{
+  volatile double d = 300;
+  volatile signed char c;
+  c = d;
+}
+
+/* { dg-final { scan-assembler-not "__ubsan_handle" } } */
diff --git gcc/testsuite/g++.dg/ubsan/return-3.C gcc/testsuite/g++.dg/ubsan/return-3.C
index e69de29..95f345d 100644
--- gcc/testsuite/g++.dg/ubsan/return-3.C
+++ gcc/testsuite/g++.dg/ubsan/return-3.C
@@ -0,0 +1,27 @@
+// { dg-do compile }
+// { dg-options "-fsanitize=return" }
+
+struct S { S (); ~S (); };
+
+S::S () {}
+S::~S () {}
+
+__attribute__((no_sanitize_undefined))
+int
+foo (int x)
+{
+  S a;
+  {
+    S b;
+    if (x)
+      return 1;
+  }
+}
+
+int
+main ()
+{
+  foo (0);
+}
+
+// { dg-final { scan-assembler-not "__ubsan_handle" } }
diff --git gcc/ubsan.c gcc/ubsan.c
index 5e1c3e7..cd44f30 100644
--- gcc/ubsan.c
+++ gcc/ubsan.c
@@ -1148,7 +1148,10 @@ public:
   virtual bool gate (function *)
     {
       return flag_sanitize & (SANITIZE_NULL | SANITIZE_SI_OVERFLOW
-			      | SANITIZE_BOOL | SANITIZE_ENUM);
+			      | SANITIZE_BOOL | SANITIZE_ENUM)
+	     && current_function_decl != 0
+	     && !lookup_attribute ("no_sanitize_undefined",
+				   DECL_ATTRIBUTES (current_function_decl));
     }
 
   virtual unsigned int execute (function *);

	Marek